The occlusion of the arteries can lead to insufficient blood flow resulting in discomfort and risks of angina and ischemia. Significant blockage of blood flow in the coronary artery can result in damage to the myocardial tissue or death of the patient. In most cases, occlusion of the artery results from progressive long term deposits of plaque along the artery wall. While such deposits may be concentrated and occlude the artery at a particular site, the deposits are most certainly present throughout the arteries and the vascular system.
Coronary artery bypass graft (CABG) surgery is a surgical procedure performed in severe cases of coronary blockages. CABG procedures involve anastomosing an artery to a vascular graft which restores the flow of blood by establishing another pathway around the occluded vasculature. One problem encountered in the procedure is the need of performing the procedure while simultaneously maintaining sufficient function of the patient""s circulatory system.
A CABG procedure may involve arresting the heart so that blood flow is diverted from the vessel to be anastomosed. The patient""s blood circulation is maintained by a cardiopulmonary bypass (CPB). This bypass is accomplished by diverting the blood flow at selected arterial locations. The blood is diverted to the bypass system for release of carbon dioxide and subsequent oxygenation. Then, the blood is returned to the patient via a pump. Examples of these procedures are found in U.S. Pat. No. 5,799,661 to Boyd et al. which discloses a device and method for performing CABG surgery for multi-vessel coronary artery disease through port-access or closed-chest thorascopic methods; and U.S. Pat. No. 5,452,733 to Sterman et al. which discusses performing grafts with an efficacy equal to or greater than conventional open surgical bypass techniques.
Another CABG procedure involves operating on a beating heart and eliminates the need for a CPB. However, the procedure still requires diverting blood flow for a proximal anastomosis, such as one which attaches graft material (e.g., a graft vessel) to the ascending aorta.
First, the blood flow may be diverted by aortic clamping. Among the drawbacks associated with aortic clamping are an increased chance of trauma to the arteries caused by ligatures at the clamped site and the possible dislodging of plaque within the clamped vessel wall. As mentioned above, the arterial bypass may be required due to the deposits of plaque which have occluded the vessel. However, the plaque is typically present throughout the artery and is not limited to the occluded location. Clamping the artery creates a risk of plaque being released into the blood stream. This release of plaque has the potential of causing a stroke, occlusion of a smaller peripheral vessel, or other vascular trauma. In a beating heart procedure, full clamping (i.e., cross clamping) of the aorta for graft attachment at the proximal anastomosis is not feasible. Therefore a side biting clamp is used to clamp off only a portion of the cross-section of the aorta, where the proximal anastomosis is performed. This type of clamping procedure poses the same risks described above with regard to cross clamping, e.g., the risk of release of plaque and resultant cause of a stroke, occlusion of a smaller peripheral vessel, or other vascular trauma.
Second, the blood flow may be diverted by the use of a balloon catheter within the aorta, such as described in U.S. Pat. No. 5,868,702, for example. Drawbacks of using a balloon catheter in creating a seal to divert blood flow include the possibility of disturbing plaque deposits and creating particles in the blood stream, the chance that the balloon catheter may move within the aorta disrupting the seal and resulting in blood loss, and trauma to aortic tissue caused by the pressure needed to create the seal.
PCT Patent WO 98/52475 to Nobles et al. attempts to address problems associated with diverting the blood flow. Nobles et al. provides a method and device for creating an area of hemostasis within a blood vessel without interrupting the flow of blood through the vessel which eliminates the need to clamp the vessel. However, the Nobles et al. device requires the withdrawal of the hemostasis device prior to obtaining a tight seal between the graft and vessel. Therefore, since the area of hemostasis is lost upon the retrieval of the hemostasis device, the artery is open and blood is lost until the sutures are tightened.
Yet another problem related to CABG procedure lies in the procedure of suturing the vessels to create a tight seal. To ensure the integrity and patency of the anastomosis, the graft and vessel to be joined must be precisely aligned with respect to each other. If one of the tissues is affixed too close to its edge, the suture can tear through the tissue and impair both the tissue and the anastomosis. Another problem is that, even after proper alignment of the tissue, it is difficult and time consuming to pass the needle through the tissues, form the knot with the suture material, and ensure that the suture material does not become entangled. These difficulties are exacerbated by the small size of the artery and graft. Another factor contributing to the difficulty of the CABG procedure is the limited time available to complete the procedure. The surgeon must complete the graft in as little time possible due to the absence of blood flowing through the artery. If blood flow is not promptly restored, sometimes in as little as 30 minutes, the tissues the artery supplies may experience significant damage or necrosis. As mentioned above, surgeons are under pressure to reduce the cross-clamp time, yet, an incomplete suture may result in a leak in the tissue approximation between the vessel and graft. Moreover, the tissue approximation must be smooth and open. Hence, the suture cannot be hastily performed.
Additionally, the difficulty of suturing a graft to an artery using minimally invasive surgical techniques, where the surgeon uses ports to access the internal organs to perform the procedure, has effectively prevented the safe use of complicated suturing technology in cardiovascular surgical procedures. Accordingly, many procedures are performed invasively and require a sternotomy, an opening of the sternum. As a result, the recovery times for patients is significantly increased. U.S. Pat. No. 5,868,763 to Spence et al. attempts to circumvent the suturing process by attaching the vessels to a cuff device. Spence et al. utilizes a passageway for continued blood flow so there is no clamping of the artery.
Houser et al., in U.S. Pat. No. 5,989,276, discloses various devices and techniques for performing bypass, one of which includes a device which can be intralumenally originated. Various other clamping arrangements are provided for securing a graft to a vessel without the use of sutures or other fasteners.
All of the problems discussed above are multiplied in those cases where a multiple anastomosis is required. In those cases where multiple bypass procedures are performed, the patient will naturally be subject to increased risks as multiple grafts must be sutured to perform the bypass.
There remains a need for improved anastomosis systems.
The present invention involves apparatus and methods for connecting tissue. This invention may, for example, be used to secure one vessel to another, such as in a vascular anastomosis while maintaining blood flow within the vessel.
According to one aspect of the invention, an anastomosis apparatus is provided comprising a tubular member having an end with an edge adapted to form an opening in a vessel wall and an anchor member, which comprises a flexible shaft and a piercing member, slidably coupled to the tubular member. Preferably, a generally circular centering disk with a plurality of spikes is also provided to slide down along the flexible shaft of the anchor member.
During the surgery, a physician pushes the shaft of the anchor member to insert the piercing member through the vessel wall. The piercing member is then pulled back against the vessel wall. Once the piercing member is in place against the inner wall of the vessel, the centering disk is put in place and pushed against the outer wall of the vessel, thereby clamping the vessel wall between the centering disk and the piercing member. The tubular member is then moved over the shaft, centered by the disk and rotated to cut an opening through the vessel wall. Thereafter, the piercing member is used to coordinate with the centering disk to retain and retrieve the tissue cut by the tubular member. Next, an occlusion member is advanced within the tubular member through the opening in the vessel wall in order to substantially occlude such opening and form an area of hemostasis. The tubular member can then be retrieved, leaving the occlusion member in place, after which a graft is slid down along the occlusion member shaft for creating an anastomosis with the vessel.
According to one embodiment, the occlusion member comprises a cannula. According to another embodiment, the occlusion member comprises a radially expandable member, which can be an expandable brush-like member, an umbrella, a flexible cup or an inflatable balloon.
According to another aspect of the invention a cannula having an end portion adapted to pierce through a vessel is provided. The cannula may be passed through a vessel wall and a graft secured to the vessel adjacent to the cannula to facilitate an anastomosis without clamping the vessel, thereby avoiding the risk of dislodgment of plaque from the inner wall of the vessel which is incurred with clamping.
According to another aspect of the invention, a trocar adapted to receive the cannula and allow it to pivot is provided. The cannula, thus, may be repositioned to pierce the vessel wall at different locations and perform multiple anastomoses without relocation of the trocar in the vessel wall.
According to another aspect of the invention, a surgical fastener or clip cartridge is provided. One or more surgical fasteners may be loaded in the cartridge with ends of each fastener selectively releasable from the cartridge to anchor in either the graft or vessel to which the graft is to be attached. According to one cartridge embodiment, first and second tubular members are slidably coupled to one another and at least one surgical fastener placed therein with one end of the fastener engaging the first tubular member and another end of the fastener engaging the second tubular member.
According to yet another aspect of the invention, a dual-stage release fastener is provided which includes a clip movable between an open and a closed configuration and having a memory biased to the closed configuration. A first mechanical restraint is coupled to a first portion of the clip and is adapted to bias the first portion toward the open configuration. A second mechanical restraint is coupled to a second portion of the clip and is adapted to bias the second portion toward the open configuration.
The first and second mechanical restraints may be independently manipulatable to allow independent closure of the first and second portions of the clip.
According to still another aspect of the invention, an anastomosis apparatus is provided comprising a tubular member having an end with an edge adapted to form an opening in a vessel wall and an anchor member, which comprises a flexible shaft and a piercing member, slidably coupled to the tubular member. Preferably, a generally circular centering disk with a plurality of spikes is also provided to slide down along the flexible shaft of the anchor member. An adapter is mounted on the tubular member that forms the opening. The adapter includes wells in which needles are held in a predetermined orientation adapted for piercing through the vessel wall from the inside out, upon passing the adapter into the vessel and then pulling it back to perform the piercing action. Two-stage release fasteners may be used in conjunction with the adapter so as to affix the fasteners to the vessel after piercing it with the needles and then fixing the fasteners to a graft in a later operation.
The above is a brief description of some advantages of the present invention and deficiencies in the prior art. Other features, advantages, and embodiments of the invention will be apparent to those skilled in the art from the following description, accompanying drawings, and claims.